CBSE Class 10 Science Revision Notes PDF

UNIT – I: CHEMICAL SUBSTANCES—NATURE AND BEHAVIOR CHAPTER-1 CHEMICAL REACTIONS AND EQUATIONS Chemical Reaction and Equations Topic-1 Concepts Covered  Chemical reaction and examples,  Skeletal an...

UNIT – I: CHEMICAL SUBSTANCES—NATURE AND BEHAVIOR CHAPTER-1 CHEMICAL REACTIONS AND EQUATIONS Chemical Reaction and Equations Topic-1 Concepts Covered  Chemical reaction and examples,  Skeletal and bal- anced chemical equation,  Steps to balance a chemical equation. Revision Notes A chemical reaction  A chemical reaction is a process in which the original substance(s) loses its nature and identity and forms new substance(s) with different properties.  Breaking of the chemical bonds and formation of new chemical bonds is responsible for the occurrence of a chemical reaction.  The substances which take part in a chemical reaction are called Reactants.  The substances which are formed in a chemical reaction are called Products.  Examples of chemical reaction: (i) Digestion of food (ii) Respiration (iii) Rusting of iron (iv) Burning of magnesium ribbon (v) Formation of curd  A chemical reaction can be identified by either of the following observations: S. No. Characteristics Examples 1. Change in state The combustion reaction of candle wax is characterized by a change in state from solid to liquid and gas. 2. Change in colour The chemical reaction between citric acid and purple coloured potassium permanganate solution is characterized by a change in colour from purple to colourless. 3. Evolution of gas The chemical reaction between zinc and dilute sulphuric acid is characterized by hydrogen gas. Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) 4. Change in temperature The reaction between quicklime and water to form slaked lime is characterized by an increase in temperature. 5. Formation of a When an aqueous solution of sodium sulphate is mixed with the aqueous precipitate solution of barium chloride, barium sulphate comes in the form of white precipitate Na2SO4 (aq)+BaCl2(aq) → BaSO4(↓)+2NaCl(aq) Chemical equations  A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae.  It is a way to represent the chemical reaction in a concise and informative way.  For example, Magnesium + Oxygen → Magnesium oxide (Reactants) (Product) This equation is called word equation.  The word equation can be written into chemical equation by writing symbols and formulae of the substance in place of their name. 2Mg + O2 → 2MgO Writing a chemical equation (i) The symbols of elements and the formulae of reacting substances (reactants) are written on the left hand side of the equation, with a plus (+) sign between them. 2 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X (ii) The symbols and formulae of the substances formed (products) are written on the right hand side of the equation, with a plus sign (+) between them. (iii) An arrow sign (→) is put between the reactants and the products. (iv) The physical states of the reactants and products are also mentioned in a chemical equation. Skeletal chemical equation: A chemical equation which simply represents the symbols and formulas of reactants and products taking part in the reaction is known as skeletal chemical equation for a reaction. For example: For the burning of Magnesium in the air, Mg + O2 → MgO is the skeletal equation. Balanced Equation: The equation in which atoms of various elements on both sides of a chemical equation are equal in accordance with the law of conservation of mass. The example of balanced chemical equation : 340 atm (i) CO(g) + 2H2 (g)  → CH3OH(l) sunlight   C6H12O6(aq) + 6O2 (g) (ii) 6CO2(g) + 6H2O(l) chlorophyll Glucose The process of equalizing the atoms of various elements both on either sides of an equation is called the balancing of chemical equation. This is known as hit and trial method. Let us understand this with the help of an example given below: Key Word Law of conservation of mass: It states that, "The matter can neither be created nor destroyed in a chemical reaction. " OR " the total mass of reactants = total mass of products". Example 1 Balancing a chemical equation : Step 1. Write the chemical equation and draw boxes around each formula. Fe + H2O → Fe3O4 + H2 Step 2. Count the number of atoms of each element on both the sides of the arrow : No. of atoms at No. of atoms at Element reactant side product side 1. Fe 1 3 2. H 2 2 3. O 1 4 Step 3. Equalize the number of the atoms of element which has the maximum number of atoms (oxygen). Fe + 4H2O → Fe3O4 + H2 Step 4. Try to equalize all the atoms of elements on reactant and product side by adding coefficient in front of it. 3Fe + 4H2O → Fe3O4 + 4H2 Now, all the atoms of elements are equal on both sides. Step 5. Write the physical states of reactants and products. 3Fe (s) + 4H2O (g) → Fe3O4 (s) + 4H2 (g) Solid state = (s), Liquid state = (l), Gaseous state = (g), Aqueous state = (aq) Step 6. Write necessary conditions of temperature, pressure or catalyst at above or below the arrow. Types of Chemical Reactions Topic-2 Concepts Covered  Combination reaction,  Decomposition reaction,  Displacement reaction,  Double displacement reaction,  Redox reaction,  Oxidation and reduction reaction,  Exothermic and endothermic reaction. Revision Notes Types of Chemical Reactions I. Combination Reaction: The reaction in which two or more reactants combine to form a single product. e.g., (i) Burning of coal C(s) + O2(g) → CO2(g) (ii) Formation of water  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 3 2H2(g) + O2(g) → 2H2O(l) (iii) CaO(s) + H2O(l) → Ca(OH)2 (aq) + Heat (Quick lime) (Slaked lime) Exothermic Reactions: Reaction in which heat is released along with formation of products. e.g., (i) Burning of natural gas. CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + Heat (ii) Respiration is also an exothermic reaction. C6H12O6(aq) + 6O2(g) → 6CO2(aq) + 6H2O(l) + energy (Glucose) II. Decomposition Reaction: The reaction in which a compound splits into two or more simpler substances is called decomposition reaction. A→B+C (a) Thermal decomposition: When decomposition is carried out by heating. e.g., (i) 2FeSO4(s) Heat   Fe2O3(s) + SO2(g) + SO3(g) (Ferrous sulphate) (Ferric oxide) Green colour Red-brown colour (ii) CaCO3(s) Heat   CaO(s) + CO2(g) (Lime stone) (Quick lime) (b) Electrolytic Decomposition: When decomposition is carried out by passing electricity. Electric e.g., 2H2O(l) current   2H2(g) + O2(g) (c) Photolytic Decomposition: When decomposition is carried out in presence of sunlight. Sunlight e.g., (i) 2AgCl(s)   2Ag(s) + Cl2(g) Sunlight (ii) 2AgBr(s)   2Ag(s) + Br2(g) Endothermic Reaction: The reactions which require energy in the form of heat, light or electricity to break reactants are called endothermic reactions. III. Displacement Reaction: The chemical reactions in which more reactive element displaces less reactive element from its salt solution. e.g., (i) Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s) (Iron) (Copper sulphate) (Ferrous sulphate) (Copper) The iron nail becomes brownish in colour by deposition of Cu and blue colour of CuSO4 changes into dirty green colour due to formation of FeSO4. (ii) Zinc displaces copper forming zinc sulphate. Zn is more reactive than copper. Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) (Zinc Sulphate) IV. Double Displacement Reaction: A reaction in which new compounds are formed by mutual exchange of ions between two compounds. Na2SO4(aq) + BaCl2(aq) → BaSO4(s) + 2NaCl(aq) (Sodium sulphate) (Barium chloride) (Barium sulphate) (Sodium chloride) White precipitate of BaSO4 is formed, so it is also called precipitation reaction. V. Oxidation and Reduction: Oxidation: Loss of electrons Reduction: Gain of electrons Mnemonics Concept: Types of decomposition reaction Mnemonics: PET Interpretations: Photolytic reaction, Electrolytic reaction, Thermal reaction Concept: Oxidation and reduction reaction Mnemonics: OIL RIG Interpretations: Oxidation Is Loss of electrons, Reduction Is Gain of electrons Concept: Types of chemical reactions Mnemonics: ROC.D3 Interpretations: Reduction, Oxidation, Combination, Decomposition, Displacement, Double Displacement 4 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Oxidation: It is a process of gaining oxygen during a reaction by an atom, molecule or ion. 2Cu + O2 Heat   2CuO Reduction: It is the gain of electrons or a decrease in the oxidation state of an atom by another atom, an ion or a molecule. CuO + H2 → Cu + H2O In this reaction, CuO is reduced to Cu and H2 is oxidised to H2O. In other words, one reactant gets oxidised while the other gets reduced. Such reactions are called oxidation-reduction reactions or redox reactions. VI. Important equation Redox (Oxidation and Reduction) Reaction : VII. Some usually asked equations in exams for balancing :  2CO(g) + O2(g) → 2CO2(g) (Carbon monoxide) (Oxygen) (Carbon dioxide) Heat  ZnCO3  ZnO + CO2  2FeSO4(s) + → Fe2O3(s) + SO2(g) + SO3(g)  Pb(NO3)2 + 2KI → 2KNO3 + PbI2 (Lead nitrate) (Potassium iodide) (Potassium nitrate) (Lead Iodide)  CaO(s) + H2O → Ca(OH)2 + Heat (Quick lime) (Slaked lime)  NaCl + AgNO3 → AgCl + NaNO3 (Sodium chloride) (Silver nitrate) (Silver chloride) (Sodium nitrate)  Ca + 2HNO3 → Ca(NO3)2 + H2↑  Mg + 2HNO3 → Mg(NO3)2 + H2↑  2Al + 3H2SO4 → Al2(SO4)3 + 3H2↑  Na2CO3 + 2HCl → 2NaCl + H2O + CO2  Ca(OH)2 + CO2 → CaCO3 + H2O  Zn + H2SO4 → ZnSO4 + H2↑  Zn + 2HCl → ZnCl2 + H2↑  4Zn +10 HNO3 → 4Zn(NO3)2 + 5H2O + N2O Heat  Zn + 2NaOH  Na2ZnO2 + H2↑ Effects of oxidation reactions in everyday life : 1. Corrosion: Corrosion is a process in which metals are deteriorated by action of air, moisture, chemicals, etc. It is a redox reaction where metal gets oxidised to metal oxide and oxygen gets reduced to oxide ion. Examples: (a) Corrosion of iron is called rusting. Iron objects when left in moist open air for sometime get coated with a reddish brown powder. The process is known as rusting. (b) Green coating on Copper articles and black coating on silver ornaments are another example of corrosion. Effects of corrosion : (a) Rusting causes damage to ships, car bodies, bridges, railings. (b) Corrosion is a wasteful process because it leads to wastage of tonnes of various metals every year and lot of money is spent to repair or replace it. Prevention of Rusting: (a) The iron articles should be painted. (b) The machine parts should be oiled and greased. (c) Galvanised iron pipes should be used for water supply. (d) Iron can be coated with chromium to prevent rusting. Mnemonics Concept: Preventive ways of rusting Interpretations: Mnemonics: POGG Painting Oiling Greasing Galvanising 2. Rancidity : Rancidity is the process of slow oxidation of oil and fat, present in the food materials resulting in the production of foul odour and taste in them. When cooked food items are placed for a long time, they become rancid and unsuitable for the consumption.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 5 Rancidity can be prevented by the following ways : (a) Storing the food in refrigerator. (b) Storing the food in air-tight container. (c) Addition of anti-oxidants to food. (d) Storing the food in flush bags with gas, such as nitrogen to prevent the oxidation process. CHAPTER-2 ACIDS, BASES AND SALTS Acids and Bases Topic-1 Concepts Covered  Definition of acids and bases,  Properties of acids and bases,  Indicators and its type,  pH scale and importance of pH in everyday life. Revision Notes Acids Acids are the substances that furnish H+ ions in aqueous solution. Acids are sour in taste. They turn blue litmus red. The example includes Sulphuric acid (H2SO4), Acetic acid (CH3COOH), Nitric acid (HNO3) etc. If in an aqueous solution, concentration of acid is low, it is called dilute solution and if concentration of acid is high, it is called concentrated solution. Those acids which dissociates into ions completely are called strong acids, e.g., H2SO4, HCl. Those acids which do not dissociate into ions completely are called weak acids, e.g., citric acid, acetic acid. Note: Although we talk of ‘taste’ of acids and bases, it is not advisable to taste any acid or base. Most of them are harmful. Similarly touching the solutions of strong acids and bases should be avoided. They may harm the skin. Some Naturally occurring acids : Natural source Acid Natural source Acid Vinegar Acetic acid Sour milk (Curd) Lactic acid Orange Citric acid Lemon Citric acid Tamarind Tartaric acid Ant sting Methanoic acid Tomato Oxalic acid Nettle sting Methanoic acid Bases Bases are those chemical compounds which are bitter in taste, soapy in touch, turn red litmus blue and give OH– ions in aqueous solution. The examples include Sodium hydroxide (NaOH), Potassium hydroxide (KOH), etc. The substances / bases which ionise completely to furnish OH- ions are called strong bases, e.g., KOH, NaOH, etc. The bases which ionise only partially are called weak bases, e.g., Mg(OH)2, Cu(OH)2, etc. Both acids and bases conduct free electric current in their aqueous solution due to the presence of free ions. Strength of an acid or base depends on the number of H+ ions or OH– ions produced by them respectively. More the H+ ions produced by an acid, stronger is the acid. More the OH– ions produced by a base, stronger is the base. Chemical compounds can cause harm to our body, some are very lethal, and therefore, we cannot rely on physical tests such as taste and appearance. In laboratory, to test whether a compound has acidic character or basic character, indicators are used. Indicators: These are the substances which change their colour / smell in different types of substances. 6 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Types of Indicators: S. Smell/Colour Smell/Colour Indicator No. In Acid Solution In Basic Solution  1. Litmus Red Blue  Natural  2. Red cabbage leaf extract Red Green  Indicator  3. Flowers of hydrangea plant Blue Pink  4. Turmeric No change Red Synthetic  1. Phenolphthalein Colourless Pink  Indicator  2. Methyl orange Red Yellow 1. Onion Characteristic smell No smell Olfactory 2. Vanilla essence Retains smell No smell Indicator 3. Clove oil Retains smell Loses smell Chemical Properties of Acids and Bases: 1. Reaction of Metals with: Acids Bases Acid + Metal → Salt + Hydrogen gas Base + Metal → Salt + Hydrogen gas e.g., 2HCl + Zn → ZnCl2 + H2 ↑ e.g., 2NaOH + Zn → Na2ZnO2 + H2 ↑ (Zinc chloride) (Sodium zincate) Test for H2 gas: Hydrogen gas released can be tested by bringing a burning candle near gas bubbles, it bursts with pop sound. 2. Reaction of Metal Carbonates / Metal Hydrogen Carbonates with: Acids Bases Acid + Metal Carbonate / Metal hydrogen Carbonate Base + Metal Carbonate / Metal Hydrogen Carbonate ↓ ↓ Salt + CO2 + H2O No Reaction e.g., 2HCl + Na2CO3 → 2NaCl + CO2 + H2O HCl + NaHCO3 → NaCl + CO2 + H2O Test for CO2: CO2 can be tested by passing it through lime water. Lime water turns milky. Ca(OH)2 + CO2 → CaCO3 + H2O When excess CO2 is passed, milkiness disappears. CaCO3 + CO2 + H2O → Ca(HCO3)2 3. Reaction of Acids and Bases With Each Other When an acid reacts with base, the hydrogen ion of acid combines with hydroxide ion of base and forms water. As these ions combine together, they form water instead of remaining free, thus both neutralize each other. Acid + Base → Salt + Water H X + MOH →MX + HOH + H (aq) + OH– (aq) → H2O(l) Since, in the reaction between an acid and a base both neutralize each other, it is also known as neutralization reaction. Example : Sodium hydroxide (a strong base) reacts with hydrochloric acid to form sodium chloride and water. NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l) Dilution of Acid and Base When a concentrated acid or base is diluted, a vigorous reaction takes place. The process is called dilution. It is an exothermic process as a lot of heat is produced. The process of forming ions in aqueous solution is called ionisation. All ionic compounds like NaCl, NaNO3, Na2SO4 form ions in aqueous solution.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 7 Key Facts We add acid to water. If we add water to acid, the high concentration of acid may produce a violent exothermic reaction. Concentrated acids and bases are corrosive; no person should touch it with bare hand or skin. In case a few drops spill on the body, a person should wash it with plenty of water. Common property between all acids and all bases l Acids give hydrogen gas when they react with metal. This shows that all acids contain hydrogen. l When acids are dissolved in water they dissociate as H+ ions. The dissociation as hydrogen ions in aqueous solution is the common property of all acids. As a result, an acid shows acidic behavior. HCl (aq) → H+(aq) + Cl- (aq) HNO3(aq) → H+(aq) + NO3 - (aq) CH3COOH (aq) → H+ (aq) + CH3COO - (aq) l As H+ ion cannot exist alone so it combines with water molecules and forms H3O+ (hydronium) ions. Example : HCl + H2O → H3O+ + Cl– H + + H 2 O → H 3 O+ Thus, acids can also be defined as ‘Substances which when dissolved in water ionize to produce hydrogen ions, H+ (aq). l Similarly, substances which when dissolved in water ionize to produce hydroxide ions, OH– (aq). Examples : When sodium hydroxide is dissolved in water, it dissociates into hydroxide and sodium ion. NaOH(s) Na+(aq) + OH– (aq) 4. Reaction of acids with metal oxides : Metal oxides react with acids to give salt and water. Metal oxide + Acid → Salt + Water Example : Copper oxide reacts with dil. hydrochloric acid to form copper chloride (salt) and water. CuO + 2HCl → CuCl2 + H2O Copper oxide Copper chloride Copper oxide is black in colour. When dilute hydrochloric acid is added in it, the colour of the solution becomes blue green due to formation of copper chloride. How strong are acid or base solutions? l Strength of an acid or base depends on the number of H+ ions or OH- ions produced by them respectively. l Based on its ability to dissociate into ions in solution, acids and bases are classified as strong acid or base and weak acid or base. (i) Strong acids : Acid which completely dissociates in water to produce large amount of hydrogen ions are called strong acids. For example hydrochloric acid (HCl), sulphuric acid (H2SO4), nitric acid (HNO3) are strong acids as they get completely ionized in water to form ions. HCl (aq) → H+(aq) + Cl- (aq) (ii) Weak acids : Acids which are partially ionized in water to produces small amount of hydrogen ions are known as weak acids. For example, acetic acid partially dissociates in water to produce small amount of hydrogen ions. CH3COOH (aq) → H+ (aq) + CH3COO -(aq) (iii) Strong bases : Bases which completely ionize in water to produce large amount of hydroxide ions are called strong bases. Examples include NaOH, KOH, etc. (iv) Weak bases : Bases which partially dissociate in water to furnish lesser amount of hydroxide ions are called weak bases. Examples include ammonium hydroxide (NH4OH) and calcium hydroxide Ca(OH)2 pH A scale for measuring H+ ion concentration in a solution. The concentrations of H+ are generally small, therefore concentrations of H+ are expressed in terms of pH. pH is defined as negative logarithm of H+ concentration or H3O+ concentration. pH = – log [H+] or pH = – log [H3O+] l pH = 7 → neutral solution l pH < 7 → acidic solution l pH > 7 → basic solution l On diluting an acid: pH increases ↑ l On diluting a base: pH decreases ↓ Key Oswaal 8 DiagramCBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Importance of pH in everyday life: l Plants and animals are pH sensitive. l Our body works within the pH range of 7 – 7.8. l When pH of rain water is less than 5.6, it is called acid rain. l Plants require a specific pH range for their healthy growth. Key Fact p in pH stands for ‘potentz’, a German word which means power. l pH of stomach is 1.5-3.0 due to secretion of HCl. In case of indigestion, acidity increases, which can be neutralised by antacids like milk of magnesia. l Tooth decay starts when pH of the mouth is lower than 5.5. To protect tooth decay, toothpastes which are basic in nature are used to neutralize the excess acid. l Many plants and animals produce certain acids to defend themselves. For example, Bee stings leave an acid into the skin, which causes pain and irritation. If a mild base like baking soda is applied on the stung area, it gives relief. Key Word Acid rain: Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Important Reaction of different solutions with different indicators : Colour change (if any) Colour change (if any) S. No. Name of the solution Phenolphthalein Blue litmus 1. Sodium carbonate turns pink no change 2. Hydrochlroic acid no change turns red 3. Sodium chloride no change no change Salts, their Properties and Uses Topic-2 Concepts Covered  Salts,  Types of salts,  Preparation and uses of Sodium Hydroxide, Bleaching powder, Baking soda, Washing soda and Plaster of Paris.. Revision Notes Salts: A salt is an ionic compound that results from the neutralisation reaction of an acid and a base. Salts are composed of related numbers of cations and anions, so that, the product is electrically neutral. Types of Salts: (i) Neutral salts : Salts produced by reaction of strong acid and strong base are neutral in nature with pH value 7. For example, sodium chloride formed by reaction between sodium hydroxide (strong base) and hydrochloric acid (strong acid). NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l) (ii) Acidic salts : Salts formed by reaction between a strong acid and weak base are acidic in nature with pH value less than 7. For example, ammonium hydroxide. It is a salt of hydrochloric acid (strong acid) and ammonium hydroxide (weak base). NH4OH (aq) + HCl(aq) → NH4Cl (aq) + H2O (l)  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 9 Key Word Neutralisation reaction: The reaction in which base or basic oxide reacts with acid or acidic oxide is called neutralisation reaction. Example : NaOH(aq) + HCl(aq) → NaCl(aq) + H2O. (iii) Basic salts : Salts formed by reaction of strong base and weak acid are basic in nature with pH value more than 7. For example, sodium carbonates. It is a salt of carbonic acid (weak acid) and sodium hydroxide (strong base). H2CO3 (aq) + 2NaOH (aq) → Na2CO3 + 2H2O (l) Common Salt (NaCl): Preparation: NaOH + HCl → NaCl + H2O Properties: 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) +Cl2 (g) + H2 (g) Users of common salt: (a) Used as daily food. (b) Used as preservative. (c) Used in manufacture of metal (Na ) and gas (Cl2) in molten state by electrolysis Sodium hydroxide (NaOH) Preparation : 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g) The process is called chlor - alkali process because of the products formed- Chlor for chlorine and alkali for sodium hydroxide. Uses : (a) Sodium hydroxide is used in making of paper, soap and detergents, for de-greasing metals, etc. (b) Chlorine gas is used in water treatment, manufacturing of PVC, pesticides, etc. (c) liquid hydrogen is used as rocket fuel, in hydrogenation process of oil to produce vegetable ghee (margarine) and in making of ammonia for fertilizers.. Bleaching Powder (CaOCl2): Preparation: It is produced by the action of chlorine on dry slaked lime. Cl2 + Ca(OH)2 → CaOCl2 + H2O Properties: (a) It has a strong smell of chlorine. (b) Soluble in water. (c) It loses Chlorine by the action of carbon di oxide. Uses: (a) Bleaching cotton and linen in textile industry. (b) Bleaching wood pulp in paper factories. (c) Oxidizing agent in chemical industries. (d) Disinfecting drinking water. Baking Soda (Sodium hydrogen carbonate) (NaHCO3): Preparation: NaCl+ H2O + CO2 + NH3 → NH4Cl + NaHCO3 Baking soda Properties: (a) It is mild non-corrosive base. (b) When it is heated during cooking, the following reaction takes place. ∆ 2NaHCO3  → Na2CO3 + H2O + CO2 Uses: (a) For making baking powder (mixture of baking soda and tartaric acid). When baking powder is heated or mixed with water, CO2 is produced which causes bread and cake to rise making them soft and spongy. NaHCO3 + H+ ® CO2 + H2O + Sodium salt of an acid (b) An ingredient in antacid. (c) Used in soda acids, fire extinguishers. Washing Soda (Na2CO3.10H2O): Preparation: Re-crystallization of sodium carbonate gives washing soda. It is a basic salt. Na2CO3 + 10H2O → Na2CO3.10H2O 10 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Properties: (a) Transparent crystalline solid. (b) It has 10 molecules of water of crystallisation. (c) It dissolves in water and the aqueous solution is alkaline. (d) It liberates Carbon dioxide when treated with Hydrochloric acid and Sulphuric acid. Uses: (a) In glass, soap and paper industry. (b) Manufacture of borax. (c) It can be used as cleaning agent. (d) It can be used for removing permanent hardness of water. Plaster of Paris (Calcium sulphate hemihydrates) (CaSO4.½H2O): Preparation: On heating gypsum CaSO4.2H2O at 373K, it loses water molecules and becomes Plaster of Paris (POP). It is white powder and on mixing with water it changes to gypsum. 1 1 CaSO4.2 H 2O → CaSO4. H 2O + 1 H 2O 2 2 1 1 Properties: CaSO4. H 2O + 1 H 2O → CaSO4.2 H 2O 2 2 Uses: (a) Doctors use POP for supporting fractured bones. (b) For making toys and material for decoration. Important salts : Common name Chemical name Chemical formula Uses Washing soda Sodium carbonate decahydrate Na2CO3.10H2O Manufacture of borax, caustic soda, softening of hard water. Baking soda Sodium hydrogen carbonate NaHCO2 Used as antacid, ingredient of baking powder. Bleaching powder Calcium oxychloride CaOCl2 Bleaching clothes, used as oxidising agent, disinfecting water, manufacture of chloroform. Plaster of Paris Calcium sulphate hemihydrate CaSO4.1/2 H2O Plastering fractured bones, making toys, decorative materials, statues. Water of crystallization Water molecules present in the crystal structure of salt are called water of crystallization and such salts are called hydrated salts. Water of crystallization is the fixed number of water molecule present in one formula unit of a salt. Examples:  Copper sulphate pentahydrate (CuSO4.5H2O) : It has five water molecules in one formula unit of copper sulphate (blue vitriol).  Sodium carbonate (Na2CO3.10H2O) : It has ten molecules of water as water of crystallization.  Gypsum (CaSO4.2H2O) : It has two molecules of water as water of crystallization. Key Diagram  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 11 CHAPTER-3 METALS AND NON-METALS Properties of Metals and Non-Metals Concepts Covered  Physical properties of Metals and non-metals,  Chemical Topic-1 properties of Metals and non-metals:,  Reaction with oxygen,  Reaction with water,  Reaction with acids,  Reaction with other metal salt solutions,  Reac- tion between metals and non-metals (ionic bond formation). Revision Notes Physical Properties of Metals and Non-metals : Property Metals Non-Metals 1. Lustre Metals have shining surface. They do not have shining surface. l Except Iodine. 2. Hardness They are generally hard. Generally soft. l Except Sodium, Lithium and Potas- l Except Diamond, a form of car- sium which are soft and can be easily bon which is the hardest natural cut with knife. substance. 3. State Exist as solids. Exist as solids or gases l Except Mercury that exists as liquid. l Except Bromine that exists as liquid. 4. Malleability Metals can be beaten into thin sheets. Non-metals are non-malleable. l Gold, Silver and Aluminium are the l They are brittle. most malleable metals. 5. Ductility Metals can be drawn into thin wires. They are non-ductile. 6. Conductor of heat & Metals are good conductors of heat and Non-metals are poor conductors of heat electricity electricity. and electricity. l Except Graphite. 7. Density and Melting Generally metals have high density and Non metals have low density and low point high melting point. melting point. l Except Sodium and Potassium 8. Sonorous Metals produce a sound on striking a They are not sonorous. hard surface. 9. Oxides Metallic oxides are basic in nature. Non-metallic oxides are acidic in nature. Chemical Properties of Metals : (A)Reaction of Metals with Air: Metals combine with oxygen to form metal oxide. Metals + O2 → Metal oxide Examples: (i) 2Cu + O2 → 2CuO Copper (II) oxide (black) (ii) 4Al + 3O2 → 2Al2O3 Aluminium oxide (iii) 2Mg + O2 → 2MgO Magnesium oxide Different metals show different reactivity towards O2.  Na and K react so vigorously with oxygen that they catch fire if kept in open. So, they are kept immersed in kerosene.  Surfaces of Mg, Al, Zn and Pb are covered with a thin layer of oxide which prevent them from further oxidation.  Fe does not burn on heating but iron fillings burn vigorously.  Cu does not burn but is coated with black copper (II) oxide.  Au and Ag do not react with oxygen. Amphoteric Oxides: Metal oxides which react with both acids as well as bases to produce salt and water are called amphoteric oxides. 12 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Examples: Al2O3 + 6HCl → 2AlCl3 + 3H2O Aluminium chloride Al2O3 + 2NaOH → 2NaAlO2 + H2O Sodium aluminate (B)Reaction of Metals with Water: Metals react with water to produce metal hydroxide and hydrogen gas. Metal + Water → Metal oxide + Hydrogen Examples: Metal oxide + Water → Metal hydroxide 2Mg + 2H2O → 2MgO + 2H2 ↑ Magnesium oxide MgO + H2O → Mg(OH)2 Magnesium hydroxide Sodium and Potassium react vigorously with water. Magnesium metal reacts with hot water to produce magnesium hydroxide and hydrogen gas. Mg + 2H2O → Mg(OH)2 + H2 Aluminium and zinc react with steam to produce metal oxide and hydrogen gas. Metals like silver, gold, copper and lead do not react with water. (C) Reactions of Metals with Acid: Metal + Dil. Acid → Salt + Hydrogen gas e.g., Mg + H2SO4 → MgSO4 + H2 Copper, mercury and silver don’t react with dilute acids. (D)Reaction of Metals with solutions of other Metal Salts: Metal A + Salt solution B → Salt solution A + Metal B  Reactive metals can displace less reactive metals from their compounds in solution form. Fe + CuSO4 → FeSO4 + Cu Reactivity or activity series of metals : All the metals do not react with the same rate. Some react very fast, some react moderately whereas others react very slowly. The series of metals in decreasing order of reactivity is called reactivity or activity series of metals. The metals at the top (K at the top most) are most reactive whereas metals at the bottom (Pt at the extreme bottom) are least reactive. Mnemonics Concept: Activity series of metals Mnemonics: Popular Scientists Can Make A Zoo InThe Low Humid Country More Satisfactorily Interpretations: P: Potassium S: Sodium C: Calcium M: Magnesium A: Aluminium Z: Zinc I: Iron T: Tin L: Lead H: Hydrogen C: Copper M: Mercury S: Silver  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 13 Reaction of Non-Metals: l Reaction with oxygen: Non- metals react with oxygen to form acidic oxides. e.g., C + O2 → CO2 l Reaction with water: Non-metals do not react with water because they do not release any electrons. l Reaction with dil. acids: No reaction. l Reaction with salt solutions: A more reactive non-metals will displace less reactive non-metal from its salt solution. l Reaction with chlorine: Non-metals react with chlorine to form their respective Chlorides. e.g., H2 + Cl2 → 2HCl lReaction with hydrogen: Non-metals react with hydrogen to form their respective hydrides. e.g., H2 + S → H2S Aqua Regia is a mixture of conc. HCl and conc. HNO3 in the ratio of 3: 1. It can dissolve gold and platinum. Aqua Regia is a strong oxidizing agent due to the formation of NOCl (Nitrosyl chloride) and chlorine produced by reaction of two acids. Reaction between metal and non-metals: l Reactivity of an element is the tendency to attain completely filled valence shells. l Atoms of metals can lose electrons from valence shells to form cations while atoms of non-metals can gain electrons in valence shell to form anions. l Opposite charged ions attract each other and held by strong electrostatic forces of attraction. l Let us understand formation of NaCl with the help of an example : Example 1 Step 1: Atomic number of sodium (Na) is 1. Atoms in last shell are 1. Step 2: Atomic number of chlorine (Cl) is 17. Atoms in last shell are 7. Step 3: So, Na gives 1 atom to chlorine. Step 4: This is complete transfer of electrons. So, it is ionic compound. Ionic compounds, Metallurgy and Corrosion Topic-2 Concepts Covered  Ionic compounds  Occurrence of Metals  Extraction of Metals  Corrosion  Alloy. Revision Notes Ionic Compounds The compounds formed by the transfer of electrons from a metal to a non-metal are called ionic compounds or electrovalent compounds. Properties of Ionic Compounds (i) Physical nature: They are solid and hard, generally brittle. Key Word Brittle: The property of a substance to get easily broken or cracked when hammered. (ii) Melting and Boiling Point: They have high melting and boiling points. (iii) Solubility: Generally soluble in water and insoluble in solvents such as kerosene, petrol, etc. (iv) Conduction of electricity: Ionic compounds conduct electricity in molten and solution form but not in solid state. 14 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Occurrence of Metals l Minerals: The elements or compounds which occur naturally in the earth’s crust are called minerals. l Ores: Minerals that contain very high percentage of particular metal and the metal can be profitably extracted from it, such minerals are called ores. Metals on the basis of reactivity, can be grouped into three categories: l Metals at the bottom of the activity series are least reactive and are often found in free state. For e.g., Gold, silver, platinum and copper. These metals are very unreactive. The oxides of these metals can be reduced to metals by heating alone. For example, cinnabar (HgS) (an ore of mercury). When it is heated in air, it is first converted into mercuric oxide which is further reduced to mercury on heating. ∆ 2HgS(s) + 3O2(g)  → 2HgO(s) + 2SO2(g) ∆ 2HgO(s)  → 2Hg(l) + O2(g) l Metals at the top of the activity series are so reactive that they are not found in nature as free state. e.g., K, Na, Ca, Mg and Al. l Metals in the middle of the activity series are moderately reactive. They are found in the earth’s crust as oxides, sulphides and carbonates. e.g., Zn, Fe, Pb, etc. The highly reactive metals are used as reducing agents because they can displace metals of lower reactivity from their compounds. For example: 3MnO2(s) + 4Al(s) → 3Mn(l) + 2Al2O3(s) + Heat Thermit reaction: Fe2O3(s) + 2Al(s) → 2Fe(l) + Al2O3(s) + Heat The amount of heat evolved is so large that the metals are produced in the molten state. This reaction is used to join railway tracks or cracked machine parts. Extraction of metals : It is the process of obtaining pure metal from its ore. Extraction of metal can be classified into three steps  : (1) Enrichment of ores or concentration of ores. (2) Extraction of metal from the concentrated ores. (3) Refining of metal. Ore Concentration of ore Metals of high Metals of medium Metals of low reactivity reactivity reactivity Electrolysis of Sulphide ores molten ore Carbonate ore Sulphide ore Roasting Pure metal Calcination Roasting Pure metal Oxide of metal Reduction to metal Purification of metal  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 15 Steps involved in extraction of metals from ores are as follows: Metallurgy: The extraction of metals from their ores and then refining them for use is known as metallurgy. Corrosion: It is the deterioration of a metal as a result of chemical reactions between it and surrounding environment. For example, l Silver reacts with sulphur in air to form silver sulphide and articles become black. l Copper reacts with moist carbon dioxide in air and forms green coat of copper carbonate. l Iron acquires a coating of brown flaky substance called rust. l Rust is hydrated Iron (III) oxide, i.e., Fe2O3.xH2O Prevention of corrosion: By painting, oiling, greasing, galvanizing and by making alloys. Galvanization: It is the process which involves coating of iron with zinc. The oxide thus formed is impervious to air and moisture thus protects further layers from getting corroded. Alloys: These are homogeneous mixture of metals with metals and non-metals. For example, l Stainless steel: Alloy of iron, nickel, chromium l Brass: Alloy of copper and zinc l Bronze: Alloy of copper and tin l Solder: Alloy of lead and tin Amalgam: If one of the metals is mercury, then the alloy is known as amalgam. E.g, Sodium amalgam and silver amalgam. CHAPTER-4 CARBON COMPOUNDS Carbon and its Properties, Homologous Series and IUPAC Names Topic-1 Concepts Covered  Covalent bonding in carbon compounds,  Versatile nature of carbon,  Homologous series,  Nomenclature of carbon compounds containing functional groups,  Difference between saturated and unsatu- rated hydrocarbons,  Chemical properties of carbon compounds Revision Notes Properties of Carbon The element carbon is non-metal. Its symbol is C. Carbon is a versatile element. The percentage of carbon present in earth's crust in form of mineral is 0.02% and in atmosphere as CO2 is 0.03%. All the living things, like plants and animals are made up of carbon based compounds. Carbon always forms covalent bonds. The atomic number of carbon is 6. Electronic configuration: K L C (6) 2 4 How carbon attain noble gas configuration ? (i) Carbon is tetravalent in nature. It does not form ionic bond because it has 4 valence electrons, half of an octet. To form ionic bonds, carbon molecules must either gain or lose 4 electrons. It is because, that is difficult to hold four extra electron and would require large amount of energy to remove four electrons. So, carbon can form bond by sharing of its electron with the electrons of other carbon atom or with other element and attain noble gas configuration. (ii) The atoms of other elements like hydrogen, oxygen, nitrogen and chlorine also form bonds by sharing of electrons. (iii) The bond formed by sharing of electrons between same or different atoms is covalent bond. 16 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Key Word Covalent Bond is formed by sharing of electrons between atoms. In a covalent bond, the shared pair of electrons belongs to the valence shell of both the atoms. Conditions for formation of a covalent bond: (i) The combining atoms should have 4 to 7 electrons in their valence shell. (ii) The combining atoms should not lose electrons easily. (iii) The combining atoms should not gain electrons readily. (iv) The difference in electronegativity of two bonded atoms should be low. Properties of covalent compounds: (i) Physical state: They are generally liquids or gases. Some covalent compounds may exist as solid. (ii) Solubility: They are generally insoluble in water and other polar solvents but soluble in organic solvents such as benzene, toluene, etc. (iii) Melting and boiling points: They generally have low melting and boiling points. (iv) Electrical conductivity: They do not conduct is more apt word instead of electrical current. Steps for writing the Lewis dot Structures of a covalent compound: (i) Write the electronic configuration of all the atoms present in the molecule. (ii) Identify how many electrons are needed by each atom to attain noble gas configuration. (iii) Share the electrons between atoms in such a way that all the atoms in a molecule have noble gas configuration. (iv) Keep in mind that the shared electrons are counted in the valence shell of both the atoms sharing it. Key Word Lewis dot structures reflect the electronic structures of the elements, including how the electrons are paired. In Lewis dot structures each dot represents an electron. A pair of dots between chemical symbols for atoms represents a bond. Let us understand this with the help of examples: Example 1 (i) H2 H – H: Single bond between hydrogen atoms (ii) O2 O = O: Double bond between oxygen atoms (iii) N2 N ≡ N: Triple bond between nitrogen atoms Versatile Nature of Carbon: Carbon can form large number of carbon compounds. The factors that enable carbon to form large number of compounds are catenation and tetravalency.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 17 Key Words Catenation: It is the unique ability of elements to form long, straight or branched chains and rings of different sizes. Carbon shows maximum catenation in the periodic table. Tetravalency: It is the state of an atom in which there are four electrons available with the atom for covalent chemical bonding. Hydrocarbon: Compounds made up of hydrogen and carbon are called hydrocarbon. Electron dot structure of saturated hydrocarbons: Ethane C2H6 Mnemonics Concept: Saturated and unsaturate compounds Mnemonics: Thank You DeSa. Interpretation: T: Triple bond Y: Alkyne D: Double bond e: Alkene S: Single bond A: Alkane Electron dot structure of unsaturated hydrocarbons: Ethene: C2H4 Ethyne: C2H2 H–CºC–H On the basis of structures, hydrocarbons can be: (i) Straight chain hydrocarbons: Propane, butane, etc. (ii) Branched chain hydrocarbon: Iso-butane, iso-pentane, etc. (iii) Cyclic hydrocarbons: Cyclohexane C6H12, benzene C6H6, etc. Cyclic or Closed Chain Hydrocarbons: These are the hydrocarbons which have carbon - carbon closed chain. They are classified as: (i) Alicyclic hydrocarbons: These are the hydrocarbons which do not have benzene ring in their structures. (ii) Aromatic hydrocarbons: The hydrocarbons which have benzene ring in their structures. When hydrogen bonded to carbon of benzene is substituted with halogens, radicals or other functional groups, the derivatives are called aromatic compounds. 18 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Benzene: It is an aromatic hydrocarbon which has the molecular formula C6H6. It has alternating carbon - carbon single and double bonds. Benzene can also be represented as: IUPAC name of hydrocarbon consists of two parts. It involves: (i) Word root: Number of carbons in the longest carbon chain. Number of carbon atoms Word root (Greek name) 1 Meth 2 Eth 3 Prop 4 But 5 Pent 6 Hex 7 Hept 8 Oct 9 Non 10 Dec (ii) Suffix: It depends on the type of carbon - carbon bond, for single bond suffix is – ane; for double bond, suffix is – ene; and for triple bond suffix is – yne. Types of Formula for Writing Hydrocarbons: (i) Molecular formula: It involves the actual number of each type of atom present in the compound. (ii) Structural formula: The actual arrangement of atoms is written in structural formula. (iii) Condensed formula: It is the shortened form of the structural formula. In hydrocarbon chain, one or more hydrogen atom is replaced by other atoms in accordance with their valencies. These are heteroatoms. These heteroatoms or group of atoms which make carbon compound reactive and decides its properties are called functional groups. Some important functional groups in carbon compounds are: Hetero atom Functional group Formula of functional group Cl/Br Halo (Chloro/Bromo) — Cl, — Br, — I Oxygen 1. Alcohol — OH 2. Aldehyde — CHO Key Word Heteroatoms: An 3. Ketone —C— atom other than carbon  or hydrogen atom. O 4. Carboxylic acid O  — C — OH Double bond 1. Alkene group >C=C< Triple bond 2. Alkyne group —C≡C— Isomerism: The compounds which possess the same molecular formula but different structural formulae, are called isomers, and the phenomenon is known as isomerism. For example, butane with a molecular formula C4H10 has two isomers.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 19 Homologous Series: A series of organic compounds in which every succeeding member differs from the previous one by – CH2 or 14 a.m.u. is called homologous series. The molecular formula of all the members of a homologous series can be derived from a general formula. Properties of a homologous series: As the molecular mass increases in a series, physical properties of the compounds show a variation, but chemical properties which are determined by a functional group remain the same within a series. Mnemonics Concept 1: Homologous series Mnemonics: Monkeys Eat Peeled Bananas Interpretations: M: Methane (1C), E: Ethane (2C), P: Propane (3C), B: Butane (4C) Concept 2: Reaction in saturated and Unsaturated compounds Mnemonics: SaSUnA Interpretations: Sa: Saturated, S: Substitution, Un: Unsaturated, A: Addition Homologous series of alkanes: General formula: CnH2n+ 2, where n = number of carbon atoms. CH4, C2H6, C3H8. Homologous series of alkenes: General formula: CnH2n, where n = number of carbon atoms. C2H4, C3H6, C4H8. Homologous series of alkynes: General formula: CnH2n–2, where n = number of carbon atoms. C2H2, C3H4, C4H6. Chemical Properties of carbon compounds (a) Combustion: Carbon compounds burn in air to give carbon dioxide, water, heat and light. CH4 + 2O2 Combustion  CO2 + 2H2O + Heat + Light l Carbon and its compounds are used as fuels because they burn in air releasing lot of heat energy. l Saturated hydrocarbon generally burn in air with blue and non-sooty flame. l Unsaturated hydrocarbon burns in air with yellow sooty flame because percentage of carbon is higher than saturated hydrocarbon which does not get completely oxidized in air. (b) Oxidation: Alcohols can be converted into carboxylic acid in the presence of oxidizing agent like alkaline KMnO4 (potassium permanganate) or acidic potassium dichromate K2Cr2O7. Alkaline KMnO Or CH3CH2OH  4 Acidic K 2 Cr2 O7  CH3COOH Ethanol Ethanoic acid (c) Addition Reaction: Unsaturated hydrocarbons (alkene, alkyne) undergo addition reactions. In unsaturated hydrocarbon, hydrogen added in the presence of catalyst palladium or nickel. Vegetable oils are converted into vegetable ghee using this process. It is also called hydrogenation of vegetable oils. (d) Substitution Reaction: Saturated hydrocarbons undergo substitution reaction in the presence of sunlight. Sunlight CH4 + Cl2  CH3Cl + HCl Ethanol, Ethanoic acid, Soaps and Detergents Topic-2 Concepts Covered  Properties and uses of ethanol and ethanoic acid,  Soap and Detergents. Revision Notes Ethanol: Ethanol is commonly known as alcohol. It is the second member of the alcohol series. The molecular formula of ethanol is C2H5OH. Chemical Properties: (i) Reaction with sodium: Formation of sodium ethoxide and hydrogen. 2CH3CH2OH + 2Na → 2CH3CH2ONa + H2 20 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X (ii)  Reaction with acid: Formation of ester (ethyl ethanoate) – a sweet smelling ester. This process is called esterification. conc conc.H. HSO SO CH 3COOH++C CH3COOH C2 2H H5OH  5OH    22 44    CH CH3COOCH 2 CH3 3++H 3COOCH2 CH H2O 2O Uses: In preparation of soap, cosmetics, in alcoholic beverages, in medicines, in laboratory reagent. Ethanoic acid: The common name of ethanoic acid is acetic acid and it belongs to the group of acids called carboxylic acid. It is the second member of the series. The molecular formula of the compound is CH3COOH. Vinegar — 5-8 % solution of acetic acid in water. Glacial acetic acid — Pure acetic acid Chemical Properties of ethanoic acid (i) Reaction with sodium carbonate: 2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2 (ii) Reaction with sodium hydrogen carbonate: CH3COOH + NaHCO3 → CH3COONa + H2O + CO2 Brisk effervescence marks the presence of carbon dioxide. (iii) Reaction with NaOH: CH3COOH + NaOH → CH3COONa + H2O (iv) Reaction with ethanol (Esterification): conc. H SO  CH 3COOH + CH 3CH 2OH  2 4    CH 3COOC 2 H 5 + H 2O Soap and detergents Soap is sodium or potassium salt of long chain carboxylic acid. e.g., C17H35COONa+ On hydrolysis, ester gives parent alcohol and sodium salt of carboxylic acid. Alkaline hydrolysis of ester is called saponification. Soaps are effective only in soft water. Detergents are ammonium or sulphonate salt of long chain of carboxylic acid. Detergents are effective in both hard and soft water. Soap molecule has: (i) Ionic (hydrophilic) part (ii) Long hydrocarbon chain (hydrophobic) part Structure of soap molecule Key Word Ester: Esters is generally sweet-smelling substances and is produced as a result of the reaction of an acid such as ethanoic acid and an alcohol such as ethanol in the presence of an acid catalyst. It is used in making perfumes and as flavouring agents. Cleansing Action of Soap: Most dirt is oily in nature. The hydrophobic end of soap molecule attaches itself with dirt and the ionic end is surrounded with molecule of water. This result in formation of a radial structure called micelles. Soap micelles helps to dissolve dirt and grease in water and cloth gets cleaned. The magnesium and calcium salt present in hard water reacts with soap molecule to form insoluble product called scum. This scum create difficulty in cleansing action. By use of detergent, insoluble scum is not formed with hard water and clothes get cleaned effectively.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 21 UNIT – II: WORLD OF LIVING CHAPTER-5 LIFE PROCESSES Nutrition Topic-1 Concepts Covered  Modes of nutrition- Autotrophic and heterotrophic Process of photosynthesis  Nutrition in human beings  Human digestive system Revision Notes All living things perform certain life processes like growth, excretion, respiration, circulation and reproduction etc. The basic functions performed by living organisms for their survival and body maintenance are called life processes. Basic life processes are: Life Processes Growth Digestion Respiration Circulation Excretion Reproduction Energy required to carry out the different life processes, is obtained from carbon-based food sources through nutrition. There are two modes of nutrition: (i) Autotrophic nutrition: It is a kind of nutrition in which organism prepare its own food by a process called photosynthesis for e.g., Green plants and some photosynthetic bacteria. (ii) Heterotrophic nutrition: It is a kind of nutrition in which an organism takes food from another organism for e.g., Animals and fungi. It is of three types: Holozoic (e.g. Amoeba, animals), Saprophytic (e.g., fungi) and Parasitic (e.g., Cuscuta, ticks and mites) Depending on the mode of nutrition, organisms are classified as autotrophs and heterotrophs. (i) Autotrophs can prepare their own food from simple inorganic sources like carbon dioxide and water. (e.g., green plants, some bacteria). (ii) Heterotrophs cannot synthesise their own food and are dependent on the autotrophs for obtaining complex organic substances for nutrition. (e.g., animals) Green plants manufacture their own food by the process of photosynthesis. Here, they utilise CO2 and H2O in presence of sunlight, with the help of chlorophyll and gives out O2 as a by-product. Main Events of Photosynthesis are: (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) Reduction of CO2 to form carbohydrates. Site of photosynthesis in the leaf is chloroplast. It contains a green colour pigment called chlorophyll. Amoeba is a unicellular organism, which follows holozoic mode of nutrition. Amoeba captures food with the help of temporary finger-like processes called pseudopodia. Plants carry out exchange of gases with surrounding atmosphere through stomata. The opening and closing of stomatal pores are controlled by the turgidity of guard cells. (i) When guard cells uptake water from surrounding cells, they swell to become a turgid body. This enlarges the pore in between and causes stomatal opening. (ii) When water is released, guard cells become flaccid. This closes the pore in between causing stomatal closing. Nutrition in human beings: The human digestive system comprises of alimentary canal and associated digestive glands. The alimentary canal is a long muscular tube extending from the mouth to the anus. Various regions are specialised to perform different functions. Associated glands include salivary gland, gastric gland, Liver and Pancreas. 22 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Mnemonics Concept: Parts of an alimentary canal in humans. Mnemonics: MOSS DJ I LA – remember this as “Kate MOSS is a DJ In LA” Interpretations: M = Mouth O = Oesophagus S = Stomach S = Small Intestine D = Duodenum J = Jejunum I = Ileum L = Large Intestine A = Anus Key Words Salivary glands: Secretes an enzyme called salivary amylase or ptyalin. It degrades starch into simple sugar. Peristaltic movement: It is a wave of contraction behind the food and expansion in the region of contained food that occurs in the alimentary canal for pushing the food from anterior to posterior ends. Key Facts  Small intestine is the site of the complete digestion of carbohydrates, proteins and fats.  Bile is secreted by liver and stored in gall bladder.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 23 Key Word Emulsification of fats is conversion of large fat pieces into very fine fat globules. Respiration Topic-2 Concepts Covered  Breakdown of glucose by various pathways  Types of respiration  Human respiratory system  Process of Breathing  Respiration in plants  Respiration in animals. Revision Notes Respiration is the process in living organisms, which involves: (i) Breathing (Gaseous exchange): Intake of oxygen from the atmosphere and release of CO2 (ii) Breakdown of simple food in order to release energy inside the cell Important Flowchart: Breakdown of Glucose by Various Pathways: Key Facts l The breakdown of sugars by yeast to make alcohol in the absence of air is called fermentation. l The accumulation of lactic acid causes muscle cramps. l Pharynx contains rings of cartilage which ensure that air passage does not collapse. l Respiration in plants occurs all through the day, but the photosynthesis process occurs in the daytime, in the presence of sunlight only. 24 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Types of Respiration: Respiration Aerobic Anaerobic Takes place in the presence of oxygen. Takes place in the absence of oxygen. Occurs in mitochondria. Occurs in cytoplasm. End products are CO2 and H2O. End products are alcohol or lactic acid. More amount of energy is released. Less amount of energy is released. Examples: Most plants and animals. Examples: Muscles, bacteria, yeast and parasitic worms etc. Human Respiratory system: Respiratory system in human serves to provide fresh oxygen to all body cells and removes harmful carbon dioxide from the body. It comprises Nostrils, Nasal cavity, Pharynx, Larynx, Trachea, Bronchi, Bronchiole, Alveoli, Blood capillaries and Lungs. Breathing involves two main processes: (a) Inspiration (Breathing IN): Inspiration is the active intake of air from atmosphere into lungs. l The path followed by fresh air (oxygen) is: External nares → Nasal cavity → Internal nares → Pharynx → Glottis → Larynx → Trachea → Bronchi → Bronchioles → Alveolar duct → Alveoli (b) Expiration (Breathing OUT): It is the passive expelling of air from the lungs. l The path followed by foul air (carbon dioxide) is: Alveoli → Alveolar duct → Bronchioles → Bronchi → Trachea → Larynx → Glottis → Pharynx → Internal nares → Nasal cavities → External nares → Outside The alveoli of lungs are richly supplied with blood and are the sites where exchange of gases (O2 and CO2) occurs between blood and atmosphere. In humans, the respiratory pigment haemoglobin carries oxygen from lungs to different tissues of the body. In plants, gaseous exchange takes place through stomata in leaves, lenticel in stems, general surface of roots and transpiration. Respiration in Animals: (i) Unicellular animals: Diffusion (ii) Earthworm: Breathe through the skin. (iii) Aquatic animals: Gills which extract dissolved oxygen in water. (iv) Insects: Tiny holes called spiracles (v) Land animals: Lungs l Terrestrial organisms use atmospheric oxygen for respiration. l Aquatic organisms use oxygen dissolved in water. The rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. Circulation and Transportation Topic-3 Concepts Covered  Human circulatory system,  Double circulation system in humans,  Circulation of blood in animals,  Transportation in Plants  Transpiration. Human Circulatory System The circulatory system in human beings consists of: A circulatory medium (blood and lymph), blood vessels (veins, arteries and capillaries) and heart. Heart is a muscular organ which is composed of cardiac muscles. It is the main pumping organ which pumps the blood to all parts of the body. Human heart is four chambered i.e., it is composed of four chambers: right atrium, right ventricle, left ventricle and left atrium. The chambers are separated by a muscular wall that prevents the mixing of the blood rich in oxygen with the blood rich in carbon dioxide. Blood pressure is the force that the blood exerts on the blood vessels. Humans have double circulation system. Blood travels twice through the heart in one complete cycle of the body. Pulmonary Circulation: Blood moves from the heart to the lungs and back to the heart. Systemic Circulation: Blood moves from the heart to rest of the body and back to the heart. Blood is a fluid connective tissue. It comprises four components- Plasma, RBCs, WBCs, and platelets. Lymph is a yellowish fluid that escapes from the blood capillaries into the intercellular spaces. Blood Vessels: There are three types of blood vessels:Arteries, veins and capillaries.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 25 Key Facts  Ventricles have thicker muscular walls as they pump blood into various organs.  A healthy normal blood pressure reading is less than 120 mm Hg systolic and 80 mm Hg diastolic. A blood pressure of 140/90 mmHg or higher indicates high blood pressure.  Valves ensures that blood does not flow backwards when the atria and ventricles contracts. Differences between arteries and veins: Arteries Veins 1. Carry oxygenated blood from heart to differ- 1. Carry deoxygenated blood from different body ent body parts except pulmonary artery. parts to the heart except pulmonary vein. 2. Also called distributing vessel. 2. Also called collecting vessel. 3. Walls thick, elastic and muscular. 3. Thin, non-muscular and less elastic. 4. Deep seated 4. Superficial as compared to arteries. 5. Have no valves 5. Have valves, which prevent backward flow of blood. Transportation in plants: There are two main conducting channels in vascular plants. These are Xylem and Phloem. Xylem Phloem 1. Transports water and minerals 1. Transports product of photosynthesis from from the roots to upper parts of leaves to the non-photosynthesising parts the plant. of the plants such as root & stem. 2. No energy is used for transport. 2. Energy is used from ATP for transport. 3. On maturity, the xylem becomes 3. Phloem exists as living soft tissue. dead tissue and gives mechanical support to the plant. Transpiration: It is the process of loss of water as vapours from aerial parts of the plant. Translocation: Transport of food from leaves (food factory) to different parts of the plant is called translocation. Excretion Topic-4 Concepts Covered  Excretion in human,  Structure of Nephron,  Urine formation,  Artificial Kidney,  Excretion in plants. Excretion in Human beings: During excretion, the harmful metabolic nitrogenous wastes like urea and uric acid generated are removed from the body. Key Word Excretion is the process of the removal of the harmful metabolic wastes from the body. Excretory system of human beings includes a pair of Kidney, a Urinary Bladder, a pair of Ureter and a Urethra. Each kidney contains many filtration units called nephrons. Nephrons are the basic filtration units of kidneys. They carry out filtration, selective reabsorption and tubular secretion to form urine in kidney, which is then passed out through the urethra, via the ureters and urinary bladder.. A Nephron is made up of a cluster of thin walled capillaries called glomerulus which is associated with a cup like structure called as Bowman's capsule and a long tube which terminates through this capsule. The renal artery brings oxygenated blood to the kidneys along with the nitrogenous wastes like urea and uric acid and many other substances. The blood gets filtered through the glomerulus and this filtrate enters the tubular part of nephron. As this filtrate moves down the tubular part, glucose, amino acids, salts and excess of water gets selectively re- absorbed by the blood vessels surrounding the tubules. 26 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X The amount of water re-absorbed depends upon: l How much excess of water is there in the body and, l How much nitrogenous wastes need to be excreted out. The fluid now flowing in the tubular part is urine, which gets collected in collecting ducts of nephrons. These collecting ducts together leave the kidney at a common point by forming the ureter. Key Fact The expulsion of urine from the body is known as micturition. Each ureter drains the urine in the urinary bladder where it is stored until the pressure of expanded bladder leads to an urge to pass it out through urethra. This bladder is a muscular structure which is under nervous control. 180 litres of filtrate is formed daily but only 2 litres is excreted out as urine so the rest is re-absorbed in the body. Urine formation in Kidneys: Urine formation involves three steps: (i) Glomerular filtration: Nitrogenous wastes, glucose, water, amino acids filter from the blood into Bowman’s capsule of the nephron. (ii) Tubular reabsorption: Useful substances from the filtrate are re-absorbed back by capillaries surrounding the nephron. (iii) Secretion: Urea, extra water and salts are secreted in the tubule which open up into the collecting duct and then into the ureter. Haemodialysis: In case of kidney failure, haemodialysis is the process of purifying blood by an artificial kidney. Excretion in plants: In plants, excretion of oxygen, CO2 and water takes place through stomata by the process of transpiration. CHAPTER-6 CONTROL AND CO-ORDINATION Control and Co-ordination in Plants Topic-1 Concepts Covered  Tropic movements in plants,  Plants hormones- Auxins, Gibberellins, Cytokinins, Abscisic acid and Ethylene. Revision Notes Introduction All the living organisms respond and react to the changes that happen in the environment around them. The changes in the environment to which the organisms respond and react are called stimuli such as light, heat, cold, smell, touch, etc. Both plants and animals respond to stimuli but in a different manner. Plant Movements: The movements of the individual plant parts or organs of a plant like shoot, root, etc, are due to some external stimuli like light, force of gravity, chemical substance, water, etc. Tropic Movement: It is the directional growth movement of a plant organ in response to an external stimulus. Growth towards the stimulus is positive tropism and growth away from the stimulus is negative tropism. Plants show two different types of movement: (A) Movement dependent on growth: It is of four types: (i) Phototropism: Growth movements of plants towards light e.g., shoots bend toward light (positively phototropic) and roots move away from light (negatively phototropic). (ii) Geotropism: Movement towards gravity. e.g., Roots of a plant are positively geotropic while shoots of a plant are negatively geotropic. (iii) Chemotropism: Movement towards chemicals. e.g., Growth of pollen tube towards ovule.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 27 (iv) Hydrotropism: Movement towards water. (B) Movement independent of growth: These are immediate response to stimulus. e.g., Drooping of leaves of "Touch me not plant" on touching it. This is known as thigmotropism. Key Fact Thermotropism is a type of growth movement in plants in response to temperature, e.g., seedlings curve towards warm side. Plant Hormones: They are the chemical compounds produced naturally in plants which control the growth and other physiological functions' at a site, far away from the place of secretion are called plant hormones or phytohormones.. They are required in very small amount and help to coordinate growth, development and responses to the environment. Key Word Hormones: They are the chemical substances which co-ordinate and control the activities of living organisms and also their growth. They are functional in small concentration at the remote site from their production. Main plant hormones are: (a) Auxins Synthesized at shoot tip. Helps the cells to grow longer. Involved in tropic movements of plants. (b) Gibberellin Helps in the growth of the stem. (c) Cytokinins Promotes cell division. Present in greater concentration in fruits and seeds. (d) Abscisic Inhibits growth. Acid Cause wilting of leaves. Also called as Stress hormone. (e) Ethylene A gaseous hormone which helps in artificial ripening of fruits. (H2C=CH2) Promotes senescence and abscission of leaves. Mnemonics Concept: Plant Hormone C - Cytokinins Mnemonics: A CAGE A - ABA (Abscisic Acid) Interpretations: G - Gibberellins A - Auxins E - Ethylene Control and Co-ordination in Animals Topic-2 Concepts Covered  Nervous System,  Voluntary and involuntary action,  Reflex action,  Animal hormones. Revision Notes Control and coordination is brought about in all animals with the help of two main systems: Nervous system and Endocrine system. Nervous system: It is the system of conducting tissues that receives the stimulus and transmits it to other parts of the body forming a network of nerves. It is involved in receiving information (sensation) and generating responses to that information (motor response). A typical neuron consists of following parts: (i) Cyton or Cell body: It is star shaped which contains nucleus with abundant cytoplasm called neuroplasm. The information acquired by it travels as an electrical impulse. (ii) Dendrite: The hair like structure protruding out from margins of cell body is called dendrite. It receives the nerve impulses. 28 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X (iii) Axon: It is the longest fiber on the cell body. It ends in several hairs like structures called axon terminals, which transmits electrical impulse from cell body to dendrite of next neuron. (iv) Myelin sheath: It is an insulator covered around the axon. (v) Synapse: It is the point of contact between the nerve ending of one neuron and dendrite of other neuron. It is the part where electrical signal is converted into chemical signal for onward transmission to next neuron. Dendrite Schwann cell Soma n Axo Nerve ending Myelin Sheath Nucleus Structure of a Neuron Important term: A chemical synapse formed by the contact between a motor neuron and a muscle fiber is called a neuromuscular junction. Functioning of neuron: Dendrites → Cell body → Axon → Nerve endings at the tip of axon → Synapse → Dendrite of next neuron The units which make up the nervous system are called nerve cells or neurons. The receptors pass the information to the brain through a type of nerve cells called sensory neurons. Motor neurons transmits the information from the brain to the effector organs, mainly muscles and glands. Nerve Impulse: It is the information in the form of chemical and electrical signals passing through neurons. These impulses are carried by dendrites towards the cell body. Key Words Neurons are structural and functional unit of nervous system. Receptors are the chemical structures made up of proteins that receive signals from both external and internal environment. Sensory neurons: The neurons which transmit impulses towards central nervous system. Synapse: The point of contact between the terminal branches of axon of one neuron with the dendrite of another neuron is called synapse. Voluntary Action: These are the actions which need thinking and are performed knowingly i.e., these are controlled by conscious thought. e.g.,: speaking to a friend, writing a letter etc. Involuntary Action: These are not under the control of the will of an individual and are automatic response to a stimulus which is not under the voluntary control of the brain. It occurs without the conscious choice of an organism. e.g.,: Touching a hot plate unknowingly. Reflex action: It is quick, sudden and immediate response of the body to a stimulus. e.g., Knee jerk, withdrawal of hand on touching hot object. Reflex arc: The pathway through which nerve impulse passes during reflex action is called reflex arc. i.e., it is a pathway through which the reflex action occurs. Stimulus Receptor Organ  (Skin) e.g., Heat Spinal Cord Response Effector Organ  (Muscles) e.g., withdrawal of hand Stimulus and Response: Stimulus is an observable or detectable change in the external or internal environment to which an organism reacts while response is the final reaction after reflex action.  Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X 29 Mnemonics Concept: Reflex Arc A: Afferent or Sensory Nerve Mnemonics: RACEE C: Centre (Brain or Spinal cord) Interpretations: E: Efferent or Motor Nerve R: Receptor E: Effector Responses are of three main types: (a) Voluntary: Controlled by fore brain for e.g., talking, writing. (b) Involuntary: Controlled by mid and hind brain for e.g., heartbeat, vomiting, respiration. (c) Reflex action: Controlled by spinal cord for e.g., withdrawal of hand on touching a hot object. Need of Reflex Actions: In some situations such as touching a hot object, pinching, etc., we need to act quickly, otherwise our body would be harmed. Hence, this response is generated from spinal cord instead of brain. Human nervous system: The nervous system of vertebrates (including humans) is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). Human Nervous System Central Nervous System Peripheral Nervous System (CNS) (PNS) Brain Spinal Cord (Cranial Nerves : (Spinal Nerves : Arise from Arise from the the brain) spinal cord) Human brain is the main coordinating centre of the body. It has three major parts: Forebrain, midbrain and hind brain. (a) Fore-brain: It is the most complex or specialized part of the brain. It consists of cerebrum. The main functions of forebrain are as follows: (i) Main thinking part of the brain. (ii) Controls the voluntary actions. (iii) Stores information (memory). (iv) Receives sensory impulses from various parts of the body and integrate it. (v) It is the centre associated with hunger. The brain is protected by the skull called the cranium and is surrounded by three membranes called the meninges. Key Fact The space between meninges is filled with a fluid called Cerebro-Spinal Fluid (CSF). The brain floats in CSF, which acts as a cushion and shock absorber, making the brain neutrally buoyant. Medulla oblongata, pons varolii and mid brain are collectively called the brain stem. Pituitary gland is the master gland which controls all other endocrine glands. (b) Mid-brain: Controls involuntary actions. (c) Hind-brain: It has three parts: (i) Cerebellum: Controls posture and balance, precision of voluntary actions. e.g., picking pen. (ii) Medulla: Controls involuntary actions. e.g., blood pressure, salivation, vomiting. (iii) Pons: Controls voluntary actions and helps in regulation of respiration. There are 31 pairs of spinal nerves and 12 pairs of cranial nerves in humans. Spinal cord is a cylindrical structure and a part of the central nervous system. It is made up of nervous tissue that extends from medulla oblongata in the brain stem to the lumbar region of vertebral column. It functions primarily in the transmission of nerve signals. 30 Oswaal CBSE Revision Notes Chapterwise & Topicwise, SCIENCE, Class-X Endocrine system: Endocrine system comprises endocrine glands and its secretion is called hormones. Hormones are chemical messengers secreted in very small amounts by specialized tissue called ductless glands. They act on target tissues/organs usually away from their source. Hormones assist the nervous system in control and coordination. Endocrine glands with the hormones names and their secretions in humans are: No. Gland Hormones Functions Target Site 1. Hypothalamus (i) Releasing hormones (RH) Regulates secretion of pituitary Pituitary gland (ii) Growth inhibiting hor- hormones. mones 2. Pituitary Gland (i) Growth hormone (GH) Controls growth-dwarfism and Various body cells gigantism. which undergo